[W10O32]4−-based POMOFs with different nuclear cobalt clusters for photoreduction of CO2 to produce syngas

Abstract

The CO₂ emissions from flue gases in traditional electricity generation and industrial sectors account for the main source of global emissions. The direct conversion of CO₂ in flue gases into value-added carbon production is a low-cost and simple process to realize a carbon neutral cycle, yet the development of an efficient catalyst to treat the CO₂ in flue gases is still in its infancy. Here, we present two polyoxometalate-based metal organic frameworks (POMOFs) with [W₁₀O₃₂]⁴⁻ as the connecting node, named Co₂(W₁₀O₃₂)(BIA)₄(CH₃CN)₄ (compound 1) and Co₄(W₁₀O₃₂)(INA)₆(CH₃CN)₄(TBA)₂ (compound 2), as catalysts for the photoreduction of CO₂ in exhaust gases. Under a pure CO₂ atmosphere, syngas is the main product and the yield of compound 1 is 72.7 μmol h⁻¹, which is ∼40% higher than that of compound 2 (54.2 μmol h⁻¹). Notably, the yield of compound 1 reaches 42.7 μmol h⁻¹ with 15% CO₂ in the flue gas, which indicates that the catalyst can not only overcome the low CO₂ concentration but also tolerate the harsh gas composition in the flue gas. In addition, density functional theory (DFT) calculations show that the charge distribution and steric hindrance of compound 1 were conducive to the reduction reaction.